//面试题1：赋值运算符函数
//题目：如下为类型CMyString的声明，请为该类型添加赋值运算符函数

#include<cstring>
#include<cstdio>

class CMyString
{
	public:
		CMyString(char* pData = nullptr);
		CMyString(const CMyString& str);
		~CMyString(void);
		
		CMyString& operator = (const CMyString& str);
		
		void Print();
		
	private:
		char* m_pData;
};

CMyString::CMyString(char *pData)
{
	if(pData == nullptr)
	{
		m_pData = new char[1];
		m_pData[0] = '\0';
	}
	else
	{
		int length = strlen(pData);
		m_pData = new char[length + 1];
		strcpy(m_pData,pData);
	}
}

CMyString::CMyString(const CMyString &str)
{
	int length = strlen(str.m_pData);
	m_pData = new char[length + 1];
	stpcpy(m_pData,str.m_pData);
}

CMyString::~CMyString()
{
	delete[] m_pData;
}

CMyString::CMyString::operator = (const CMyString& str)
{
	if(this == &str)
	{
		return *this;
	}
	delete []m_pData;
	m_pData = nullptr;
	
	m_pData = new char[strlen(str.m_pData) + 1];
	stpcpy(m_pData,str.m_pData);
	
	return *this;
}

//================测试代码=============
void CMyString::Print()
{
	printf("%s",m_pData);
}

void Test1()
{
	printf("Test1 begins:\n");
	
	char* text = "Hello world";
	
	CMyString str1(text);
	CMyString str2;
	str2 = str1;
	
	printf("The expected result is: %s.\n", text);
	
	printf("The actual result is: ");
	str2.Print();
	printf(".\n");
}

//赋值给自己
void Test2()
{
	printf("Test2 begins:\n");
	char* text = "Hello world";
	
	CMyString str1(text);
	str1 = str1;
	
	printf("The expected result is: %s.\n", text);
	
	printf("The actual result is: ");
	str1.Print();
	printf(".\n");
}

//连续赋值
void Test3()
{
	printf("Test3 begins:\n");
	
	char* text = "Hello world";
	
	CMyString str1(text);
	CMyString str2,str3;
	str3 = str2 = str1;
	
	printf("The expected result is: %s.\n", text);
	
	printf("The actual result is: ");
	str2.Print();
	printf(".\n");
	
	printf("The expected result is: %s.\n", text);
	
	printf("The actual result is: ");
	str3.Print();
	printf(".\n");
}

int main(int argc, char* argv[])
{
	Test1();
	Test2();
	Test3();
	
	return 0;
}










